In recent years, in the fields of semiconductors, liquid crystals, etc., miniaturization of devices by shortening the wavelength for the light source used in the lithography process has been rapidly taking place. Presently, the lithography technique using the KrF excimer laser (248 nm) for the light source has become the mainstream. To achieve further miniaturization, ArF excimer laser (193 nm) is about to be in use.
The structure of photoresist resin which can be suitably used is varied depending on the wavelength for the light source. In the event of using the KrF excimer laser light, polyhydroxy styrene with high transmissivity and derivatives thereof are popularly used. However, these have an aromatic ring that absorbs ultraviolet light at 200 nm or lower wavelength in its structure. Consequently, in the event that photoresist is formed by the use of the ArF excimer laser, the majority of exposure light is absorbed at the photoresist surface and the exposure light is difficult to transmit the resist inside, and consequently, it becomes difficult to accurately form the photoresist patterns.
In recent years, a large number of (meth)acrylates with alicyclic structure have been proposed as material of photoresists for higher density processing. Above all, ester compounds obtained by allowing 5-hydroxy-2,6-norbornane carbolactone to directly react with (meth)acrylic acid have no aromatic ring in their structures and in addition, polymers obtained by the use of the compounds provide superb dry-etching resistance, attracting keen attention of the people in various industries (Patent Literature 1).    Patent literature 1: Japanese Patent No. 3042618